Two of the off-season 's longest-running transfer sagas were finally concluded when French international Samir Nasri signed for Manchester City , while winger Juan Mata agreed to leave Valencia for Chelsea .

Nasri -- who signed for Arsenal in 2008 from Olympique Marseille -- signed a four-year deal , making him City 's fourth big-money capture of the current transfer window following the arrivals of Gael Clichy , Sergio Aguero and Stefan Savic .

`` I think he is a fantastic player because he has technique -LSB- and a good -RSB- mentality , '' Manchester City coach Roberto Mancini told the club 's official web site .

`` I know him from when he played for Marseille because I followed him when I was at Inter ... but in the last four years in the Premier League he improved a lot and now I think he 's a top player . ''

The move took place a few hours before an injury-hit Arsenal met Udinese in a crucial European Champions League second leg qualification match .

The Gunners take a slender 1-0 lead to Italy . If Nasri had played he would have been ineligible to appear in Manchester City 's own Champions League campaign , potentially jeopardizing the move .

`` It 's a big relief . It was a long , long negotiation , '' Nasri said in an interview , also with the club 's official web site .

`` Now I am City player which is what I wanted from the start . ''

`` I was a little frustrated , I told the -LSB- Arsenal -RSB- manager -LSB- Arsene Wenger -RSB- I wanted to leave ... Today is a big day for me . It is a new start . ''

In west London , Chelsea announced that they too had signed one of Europe 's most coveted wide players with the capture of Spanish international Juan Mata .

The 23 year old -- who has already won 11 caps for the world champions -- trained with the squad and will be available for Saturday 's English Premier League match against Norwich City .

`` Right from the first moment there have been good feelings all around me , '' Mata told Chelsea 's official web site .

`` Valencia was a big club anyway but I have left to join a bigger club and it is all about the opportunity to win trophies and I have that here . ''

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Manchester City has announced the signing of Samir Nasri from Arsenal

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It 's the fourth big-money signing to join City this transfer window

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Meanwhile Chelsea sign Spain winger Juan Mata from Valencia

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Mata likely to make EPL debut against Norwich City Saturday